1. Field of the Invention
The present invention relates to a catalyst-aided chemical processing method, and more particularly to a catalyst-aided chemical processing method for processing a workpiece by using an active species which is generated by dissociating a molecule in a processing solution with a catalyst.
2. Description of the Related Art
Mechanical processing methods have long been used in various fields. A mechanical polishing method, for example, involves pressing a tool against a surface to be processed so as to process the surface by creating defects in the surface and taking away surface atoms through a mechanical action. Such a mechanical polishing method causes damage to a crystal lattice and, in addition, can hardly provide a high-precision processed surface. In order to process a workpiece with high precision, it is necessary to use a chemical processing method which can process the workpiece without producing a lattice defect in it.
A processing method called EEM (elastic emission machining) is known which involves allowing a suspension of ultrafine powder to flow along a processing surface of a workpiece so as to bring the ultrafine powder into contact with the processing surface, without applying a substantial load on it, and processes the processing surface by removing surface atoms of the processing surface on the order of atomic unit through an interaction (sort of chemical bonding) between the ultrafine powder and the processing surface (Japanese Patent Laid-Open Publication No. 2000-167770 and Japanese Patent Publications Nos. 2-25745, 7-16870 and 6-44989). Further, plasma CVM (chemical vaporization machining) has been proposed which is a processing method comprising supplying a neutral radical, which has been produced by decomposition of a reactive gas caused by high-voltage application to a processing electrode, to a processing surface of a workpiece while moving the processing electrode relative to the processing surface, thereby processing the processing surface through vaporization and removal of a volatile compound produced by a radical reaction between the neutral radical and an atom or a molecule of the processing surface (Japanese Patent No. 2962583). Upon the processing, the processing time is numerically controlled based on processing time-processing amount correlation data, determined by the type of the reactive gas and the material of the workpiece, and also on coordinate data regarding a pre-processing surface and an intended post-processing surface and according to the coordinate difference. A high-efficiency processing method, utilizing a high-density radical reaction, has also been proposed which involves rotating a rotary electrode at a high speed to bring in a gas with a surface of the rotating electrode, thereby creating a flow of the gas that passes through a processing gap (Japanese Patent No. 3069271).
The above-described EEM and plasma CVM are both excellent chemical processing methods. The EEM method can provide a flat processed surface at anatomic level. High-efficient processing, comparable to mechanical processing, can be effected with high precision by plasma CVM.
As will be appreciated from the processing principle of EEM, it is possible with EEM to obtain a very flat processed surface for a high-frequency space wavelength. In EEM, fine particles are supplied by ultrapure water to a processing surface of a workpiece, and processing progresses through chemical bonding between atoms of surfaces of the fine particles and atoms of the processing surface. The surfaces of the fine particles constitute a very flat surface and the flat surface is considered to be transferred as a base surface to the processing surface. It is therefore possible to obtain a flat processed surface of an atomic order without disordering atomic arrangement. Because of the processing principle, however, it is difficult with EEM to flatten a processing surface for a space wavelength range of not less than several tens of μm.
Because of the use of an active radical, plasma CVM is a highly-effective processing method. Plasma CVM utilizes a chemical reaction between a neutral radical in plasma and a surface of a workpiece. In particular, processing is carried out by generating high-density plasma in a high-pressure atmosphere of 1 atom and causing a neutral radical generated in the plasma to act on an atom of a surface of a workpiece to convert the atom into a volatile substance. Plasma CVM can thus process a processing surface with a high processing efficiency, comparable to conventional mechanical processing, without entailing disorder of atomic arrangement in the processing surface. With no base surface, however, the processing is likely to be affected by the plane index of the processing surface.